Ex vivo and in vivo methods and related compositions for generating hematopoietic stem cell populations

Abstract

Various embodiments provide methods and related compositions for increasing the population size of hematopoietic stem cells (HSCs) in patients that may benefit from reconstitution of stem cells and/or differentiated cells of the blood lineage. The present methods enable the production of HSCs ex vivo and in vivo by reducing latexin expression and/or latexin activity within HSC exposed to various antagonists. Inhibition of latexin expression and/or latexin activity by various antagonists can promote HSC proliferation and/or inhibit HSC apoptosis. Antagonists that can reduce latexin expression and/or latexin activity can be utilized to regenerate endogenous HSCs within patients affected with disorders, diseases, cancers, or therapies for such conditions, that result in the depletion or reduction in HSCs.

1. An ex vivo method for producing a renewed population of hematopoietic stem cells (HSCs), the method comprising:
 obtaining a first HSC population from a donor; 
 contacting the first HSC population with an antagonist that reduces the expression and/or the activity of latexin; and 
 culturing the HSC population under in vitro conditions that promote cell proliferation and/or inhibit apoptosis to obtain a second HSC population that comprises a progeny of the first HSC population, 
 wherein latexin includes a latexin polynucleotide variant and/or a latexin polypeptide variant that interacts with the antagonist. 
 
     
     
       2. The ex vivo method of  claim 1 , wherein obtaining the first HSC population from the donor further comprises isolating a HSC population from a mixture of cells obtained from a biopsy removed from the donor. 
     
     
       3. The ex vivo method of  claim 1 , wherein the first HSC population and the second HSC population comprise HSCs that express any of the following combination of cell surface markers:
 Thy-1 lo  Sca-1 +  Lineage −  c-kit + ; or 
 CD150 +  CD48 −  Sca-1 +  Lineage −  c-kit + ; or 
 Thy-1 lo  CD150 +  CD48 −  Sca-1 +  Lineage −  c-kit + . 
 
     
     
       4. The ex vivo method of  claim 1 , wherein latexin expression and/or latexin activity includes intracellular processes that regulate latexin promoter activation, transcriptional activation, transcriptional termination, post-transcriptional processing, translational initiation, translational elongation, translational termination, and post-translational modification. 
     
     
       5. The ex vivo method of  claim 1 , wherein the antagonist is selected from the group consisting of: SiRNAs, ribozymes, and anti-sense oligodeoxynucleotides. 
     
     
       6. The ex vivo method of  claim 1 , wherein the antagonist can promote HSC proliferation by at least 25%. 
     
     
       7. The ex vivo method of  claim 1 , wherein the latexin polynucleotide variant has at least 70% sequence similarity to SEQ ID NO: 1. 
     
     
       8. The method of  claim 1 , wherein the latexin polypeptide variant has at least 70% sequence similarity to SEQ ID NO: 2. 
     
     
       9. A method for reconstituting a recipient host with a population of hematopoietic stem cells (HSCs) generated ex vivo, the method comprising:
 obtaining a first HSC population from a donor; 
 contacting the first HSC population with an antagonist that reduces the expression and/or the activity of latexin; 
 culturing the HSC population under in vitro conditions that promote cell proliferation and/or inhibit apoptosis to obtain a second HSC population comprising a progeny of the first HSC population; and 
 providing the second HSC population to the recipient host in need of HSC reconstitution, 
 wherein latexin includes a latexin polynucleotide variant and/or a latexin polypeptide variant that interacts with the antagonist. 
 
     
     
       10. The method of  claim 9 , wherein the first HSC population and the second HSC population comprise HSCs that express any of the following combination of cell surface markers:
 Thy-1 lo  Sca-1 +  Lineage −  c-kit + ; or 
 CD150 +  CD48 −  Sca-1 +  Lineage −  c-kit + ; or 
 Thy-1 lo  CD150 +  CD48 −  Sca-1 +  Lineage −  c-kit + . 
 
     
     
       11. The method of  claim 9 , wherein the donor is the same organism as the recipient host in that the donor has identical HLA haplotype as the recipient host, and wherein the recipient host is reconstituted with autologous HSCs when provided with the second HSC population. 
     
     
       12. The method of  claim 9 , wherein the donor is not the same organism as the recipient host, and the donor has a HLA haplotype of sufficient similarity to the HLA haplotype of the recipient host, and wherein the recipient host is reconstituted with allogenic HSCs when provided with the second HSC population. 
     
     
       13. The method of  claim 9 , wherein the antagonist is selected from the group consisting of: SiRNAs, ribozymes, and anti-sense oligodeoxynucleotides. 
     
     
       14. The method of  claim 9 , wherein the antagonist can promote HSC proliferation by at least 25%. 
     
     
       15. The method of  claim 9 , wherein the latexin polynucleotide variant has at least 70% sequence similarity to SEQ ID NO: 1. 
     
     
       16. The method of  claim 9 , wherein the latexin polypeptide variant has at least 70% sequence similarity to SEQ ID NO: 2. 
     
     
       17. The method of  claim 9 , wherein the recipient host is affected with a disease of the blood, a disease of the bone marrow, a cancer of the blood, a cancer of the bone marrow, an immunological disorder, anemia, leukemia, thalassemia major, sickle-cell disease, myelodysplastic syndrome, lymphoma, aplastic anemia, and/or multiple myeloma.